Optical properties including radiative quantum efficiencies, cross-relaxation coefficients, refractive index, energy-gap law parameters, and maximum phonon energy are presented for a new low-phonon-frequency, nonhygroscopic host crystal potassium lead chloride (KPb2Cl5) doped with Dy3+ and Nd3+. Assuming that the total decay rate (W) from each level is composed of radiative (Arad), multiphonon (WMP), and concentration-dependent cross-relaxation (Wc) rates (W=Arad+WMP+Wc), we determined radiative quantum efficiencies (ηrad=Arad/W) from emission data for five samples of various Dy3+ concentrations (N0). These results were compared with values calculated from a Judd–Ofelt analysis of the absorption spectrum. This technique required identification of cross-relaxation pathways. A cross-relaxation coefficient k=1.83×10−37 cm6 s−1 (where Wc=kN02) was measured for the Dy3+ 6H9/2+6F11/2 level. The measured multiphonon decay rates yielded energy-gap law (WMP[ΔE]≈B exp[−βΔE]) parameters B=3.72×109 s−1 and β=1.16× 10−2 cm, indicating that laser action should be possible to near 9 μm (ΔE=1100 cm−1) in this laser host at room temperature.
© 2001 Optical Society of America
(140.3380) Lasers and laser optics : Laser materials
(140.3580) Lasers and laser optics : Lasers, solid-state
(140.5680) Lasers and laser optics : Rare earth and transition metal solid-state lasers
M. C. Nostrand, R. H. Page, S. A. Payne, L. I. Isaenko, and A. P. Yelisseyev, "Optical properties of Dy3+- and Nd3+-doped KPb2Cl5," J. Opt. Soc. Am. B 18, 264-276 (2001)